KASAN: slab-use-after-free Read in ep_open

Status: upstream: reported C repro on 2026/07/31 01:28
Subsystems: usb
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+df9e891bf8ea586f846b@syzkaller.appspotmail.com
First crash: 7d20h, last: 58m
✨ AI Patch Versions (2)
Version Stage Reported Report Link Job
1 upstream 2026/07/31 13:24 Discussion ae49a838-5eb9-4227-93a3-56ad2313483a
1 moderation 2026/07/31 08:13 Discussion ae49a838-5eb9-4227-93a3-56ad2313483a
✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision Error
ae49a838 patching KASAN: slab-use-after-free Read in ep_open 2026/07/31 06:20 2026/07/31 06:20 2026/07/31 08:13 aaffb173

			
		
f708a4a5 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ KASAN: slab-use-after-free Read in ep_open 2026/07/28 00:00 2026/07/28 00:00 2026/07/28 00:42 4cb2b096

			
		
Discussions (4)
Title Replies (including bot) Last reply
[PATCH v2] usb: gadgetfs: fix use-after-free in ep_open() 1 (1) 2026/07/31 23:06
[PATCH] usb: gadgetfs: fix use-after-free in ep_open() 1 (1) 2026/07/31 13:24
[PATCH] usb: gadgetfs: fix use-after-free in ep_open() 4 (4) 2026/07/31 13:22
[syzbot] [usb?] KASAN: slab-use-after-free Read in ep_open 0 (5) 2026/07/31 11:40
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 KASAN: slab-use-after-free Read in ep_open 19 syz 2 2d00h 2d09h 0/2 upstream: reported syz repro on 2026/08/01 12:04
Last patch testing requests (4)
Created Duration User Patch Repo Result
2026/07/31 11:40 2h36m kartikey406@gmail.com patch git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci OK log
2026/07/31 08:09 34m kartikey406@gmail.com patch git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci OK log
2026/07/31 04:44 1h17m kartikey406@gmail.com patch git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2026/07/31 04:26 55m kartikey406@gmail.com patch git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in __mutex_lock_common kernel/locking/mutex.c:625 [inline]
BUG: KASAN: slab-use-after-free in __mutex_lock+0x15ca/0x1bd0 kernel/locking/mutex.c:821
Read of size 8 at addr ffff88802b0bdc58 by task syz-executor/7056

CPU: 1 UID: 0 PID: 7056 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x13d/0x4b0 mm/kasan/report.c:482
 kasan_report+0xdf/0x1c0 mm/kasan/report.c:595
 __mutex_lock_common kernel/locking/mutex.c:625 [inline]
 __mutex_lock+0x15ca/0x1bd0 kernel/locking/mutex.c:821
 ep_open+0x4c/0x2c0 drivers/usb/gadget/legacy/inode.c:823
 do_dentry_open+0x6ab/0x14d0 fs/open.c:947
 vfs_open+0x82/0x3f0 fs/open.c:1052
 do_open fs/namei.c:4700 [inline]
 path_openat+0x2873/0x4280 fs/namei.c:4863
 do_file_open+0x20e/0x430 fs/namei.c:4892
 do_sys_openat2+0x10f/0x1e0 fs/open.c:1368
 do_sys_open fs/open.c:1374 [inline]
 __do_sys_openat fs/open.c:1390 [inline]
 __se_sys_openat fs/open.c:1385 [inline]
 __x64_sys_openat+0x12d/0x210 fs/open.c:1385
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdbda55e84e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007ffc712bca48 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000555556a38500 RCX: 00007fdbda55e84e
RDX: 0000000000000000 RSI: 00007ffc712bcbb0 RDI: ffffffffffffff9c
RBP: 00007ffc712bcbb0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc712bdca0
R13: 00007fdbda63445c R14: 0000555556a384e8 R15: 0000000000000006
 </TASK>

Allocated by task 7251:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x2e5/0x6c0 mm/slub.c:5489
 _kmalloc_noprof include/linux/slab.h:988 [inline]
 _kzalloc_noprof include/linux/slab.h:1309 [inline]
 activate_ep_files drivers/usb/gadget/legacy/inode.c:1601 [inline]
 gadgetfs_bind+0x582/0x890 drivers/usb/gadget/legacy/inode.c:1692
 gadget_bind_driver+0x28c/0xbf0 drivers/usb/gadget/udc/core.c:1662
 call_driver_probe drivers/base/dd.c:628 [inline]
 really_probe+0x241/0xa60 drivers/base/dd.c:706
 __driver_probe_device+0x20e/0x450 drivers/base/dd.c:868
 driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
 __driver_attach+0x21f/0x5b0 drivers/base/dd.c:1292
 bus_for_each_dev+0x13e/0x1d0 drivers/base/bus.c:383
 bus_add_driver+0x305/0x5b0 drivers/base/bus.c:763
 driver_register+0x1e2/0x360 drivers/base/driver.c:174
 usb_gadget_register_driver_owner+0x132/0x210 drivers/usb/gadget/udc/core.c:1752
 dev_config+0xdce/0x1610 drivers/usb/gadget/legacy/inode.c:1883
 vfs_write+0x2aa/0x1050 fs/read_write.c:685
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 7252:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2677 [inline]
 slab_free mm/slub.c:6377 [inline]
 kfree+0x22b/0x6c0 mm/slub.c:6692
 put_ep drivers/usb/gadget/legacy/inode.c:225 [inline]
 put_ep+0x117/0x150 drivers/usb/gadget/legacy/inode.c:217
 destroy_ep_files+0x163/0x420 drivers/usb/gadget/legacy/inode.c:1582
 gadgetfs_unbind+0x139/0x260 drivers/usb/gadget/legacy/inode.c:1655
 gadget_unbind_driver+0x20c/0x4f0 drivers/usb/gadget/udc/core.c:1724
 device_remove+0xcb/0x180 drivers/base/dd.c:616
 __device_release_driver drivers/base/dd.c:1349 [inline]
 device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
 driver_detach+0xd8/0x1b0 drivers/base/dd.c:1435
 bus_remove_driver+0x13b/0x2e0 drivers/base/bus.c:832
 driver_unregister+0x76/0xb0 drivers/base/driver.c:202
 usb_gadget_unregister_driver+0x49/0x70 drivers/usb/gadget/udc/core.c:1784
 dev_release+0x132/0x1b0 drivers/usb/gadget/legacy/inode.c:1198
 __fput+0x3ff/0xb50 fs/file_table.c:512
 task_work_run+0x150/0x240 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x951/0x2ae0 kernel/exit.c:1009
 __do_sys_exit kernel/exit.c:1119 [inline]
 __se_sys_exit kernel/exit.c:1117 [inline]
 __x64_sys_exit+0x42/0x50 kernel/exit.c:1117
 x64_sys_call+0x152e/0x1530 arch/x86/include/generated/asm/syscalls_64.h:61
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88802b0bdc00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 88 bytes inside of
 freed 512-byte region [ffff88802b0bdc00, ffff88802b0bde00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88802b0bc000 pfn:0x2b0bc
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000240 ffff88801bc42c80 ffffea0000d57310 ffffea000164e910
raw: ffff88802b0bc000 000000080010000e 00000000f5000000 0000000000000000
head: 00fff00000000240 ffff88801bc42c80 ffffea0000d57310 ffffea000164e910
head: ffff88802b0bc000 000000080010000e 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffffffffffff01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5148, tgid 5148 (udevd), ts 26046931052, free_ts 25657143359
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1859
 prep_new_page mm/page_alloc.c:1867 [inline]
 get_page_from_freelist+0xf48/0x3530 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x299/0x2dc0 mm/page_alloc.c:5304
 alloc_slab_page mm/slub.c:3266 [inline]
 allocate_slab mm/slub.c:3380 [inline]
 new_slab+0xa2/0x640 mm/slub.c:3426
 refill_objects+0xe3/0x410 mm/slub.c:7310
 refill_sheaf mm/slub.c:2804 [inline]
 __pcs_replace_empty_main+0x376/0x680 mm/slub.c:4675
 alloc_from_pcs mm/slub.c:4773 [inline]
 slab_alloc_node mm/slub.c:4905 [inline]
 __kmalloc_cache_noprof+0x479/0x6c0 mm/slub.c:5485
 _kmalloc_noprof include/linux/slab.h:988 [inline]
 _kzalloc_noprof include/linux/slab.h:1309 [inline]
 kernfs_fop_open+0x23d/0xd50 fs/kernfs/file.c:634
 do_dentry_open+0x6ab/0x14d0 fs/open.c:947
 vfs_open+0x82/0x3f0 fs/open.c:1052
 do_open fs/namei.c:4700 [inline]
 path_openat+0x2873/0x4280 fs/namei.c:4863
 do_file_open+0x20e/0x430 fs/namei.c:4892
 do_sys_openat2+0x10f/0x1e0 fs/open.c:1368
 do_sys_open fs/open.c:1374 [inline]
 __do_sys_openat fs/open.c:1390 [inline]
 __se_sys_openat fs/open.c:1385 [inline]
 __x64_sys_openat+0x12d/0x210 fs/open.c:1385
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5154 tgid 5154 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1406 [inline]
 __free_frozen_pages+0x79f/0x1090 mm/page_alloc.c:2950
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4584 [inline]
 slab_alloc_node mm/slub.c:4917 [inline]
 __do_kmalloc_node mm/slub.c:5333 [inline]
 __kvmalloc_node_noprof+0x2eb/0x970 mm/slub.c:6905
 seq_buf_alloc fs/seq_file.c:39 [inline]
 seq_read_iter+0x819/0x1270 fs/seq_file.c:211
 kernfs_fop_read_iter+0x46c/0x610 fs/kernfs/file.c:290
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x82e/0xb40 fs/read_write.c:574
 ksys_read+0x12a/0x250 fs/read_write.c:716
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88802b0bdb00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88802b0bdb80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802b0bdc00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff88802b0bdc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802b0bdd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (19):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/03 20:47 upstream 075b74841bd0 bdd50915 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in ep_open
2026/07/27 11:24 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 365f9c7a6b81 492bab15 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: slab-use-after-free Read in ep_open
2026/07/27 09:47 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 365f9c7a6b81 492bab15 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: slab-use-after-free Read in ep_open
2026/07/27 07:02 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 365f9c7a6b81 492bab15 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: slab-use-after-free Read in ep_open
2026/08/01 23:12 upstream 02dc699f83d0 e611ffe1 .config console log report syz / log [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in ep_open
2026/08/01 18:16 upstream 02dc699f83d0 e611ffe1 .config console log report syz / log [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in ep_open
2026/07/27 08:24 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 365f9c7a6b81 492bab15 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: slab-use-after-free Read in ep_open
2026/07/27 05:28 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 365f9c7a6b81 492bab15 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: slab-use-after-free Read in ep_open
2026/07/27 03:13 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 365f9c7a6b81 492bab15 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: slab-use-after-free Read in ep_open
2026/08/03 18:23 upstream 075b74841bd0 a68cb31b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: slab-use-after-free Read in ep_open
2026/08/02 19:26 upstream 2d2338c93da7 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in ep_open
2026/08/02 19:24 upstream 2d2338c93da7 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in ep_open
2026/07/31 16:19 upstream 8ba098e6b6ff 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in ep_open
2026/07/31 03:36 upstream 3708dd948844 aaffb173 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 KASAN: slab-use-after-free Read in ep_open
2026/07/31 23:07 linux-next cc2b5f627e8c 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce KASAN: slab-use-after-free Read in ep_open
2026/08/02 10:41 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci e2d5e23967d0 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: slab-use-after-free Read in ep_open
2026/08/01 03:12 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci e2d5e23967d0 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: slab-use-after-free Read in ep_open
2026/07/29 06:29 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 365f9c7a6b81 19622d9d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: slab-use-after-free Read in ep_open
2026/07/27 01:25 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 365f9c7a6b81 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: slab-use-after-free Read in ep_open
* Struck through repros no longer work on HEAD.